1. Technical Field
The present invention relates to a blood purification method that can elevate blood purification efficiency, more concretely to a blood purification method that can control blood purification by confirming the patient's blood condition, and that can elevate purification efficiency such as water removal or removal of waste products, solutes and the like.
2. Background Art
For treating patients with impaired kidney function, blood purification such as hemodialysis or peritoneal dialysis and the like have been carried out conventionally. Hemodialysis is a treatment to purify blood by removing extra water or waste products and toxic agents in the blood, via a semipermeable membrane in form of hollow fiber. Thus, as for an apparatus that carries out hemodialysis, it is important to maintain adequately the patient's blood condition (blood volume circulating in the body) to carry out safe and effective hemodialysis. In case the target dialysis condition is an excessive setting for the patient, the blood circulating volume will decrease excessively and it may cause reduction of blood pressure or shock. On the contrary, if the dialysis condition is too gentle, there is a problem of hypertension or heart failure caused by insufficient water removal. Furthermore, naturally, it will be hard to improve symptoms of kidney failure according to insufficient dialysis.
Therefore, a hemodialysis apparatus performing water removal by monitoring a patient's blood condition have been proposed. For example, an apparatus that controls dialysis treatment by carrying out hemodialysis by measuring the Hematoerit level, and that gears and controls the blood pump, the water removal pump and the liquid supply pump, according to the blood circulating volume calculated from the Hematocrit level can be exemplified. The apparatus mentioned above has a simple construction so that anyone can use, but on the contrary, the adjustment of the dialysis time is difficult (extension of dialysis time is fatal), therefore, there was a problem that the control of the former part of the dialysis cannot be performed and that it is effective only to the reduction of blood pressure of the latter part.
In Japanese Laid-Open Patent Application No. 9-149935, a hemodialysis apparatus that controls the dialysis condition by monitoring the blood condition is disclosed. Moreover, in Japanese Laid-Open Patent Publication No. 6-83723, a controlling apparatus that estimates the body fluid condition with the Hematocrit level, and controls the blood pump or the ultra pressure according to said condition. However, as for the apparatus described above, there were problems that there were no safety mechanism to suppress the feedback control being out-of-control, or that the operator had to operate thedialysis condition or the apparatus each time the blood condition departs from the defined condition.
Furthermore, the present inventors also have proposed in the past, a blood purification apparatus that can carry out hemodialysis treatment by monitoring the patient's blood condition. For example, the blood purification apparatus disclosed in Japanese Patent Application No. 10-101324 (Japanese Laid-Open Patent Application No. 11-221275) can be exemplified. However, as this apparatus gains the water removal volume in the former part of the dialysis, it has a merit of being able to control the blood circulating volume during dialysis within the predetermined range which can solve the problem of extension of dialysis time. But, on the contrary, it had demerits that it was necessary to define an alarm zone to control, that it was necessary to define controlling parameters in detail.
There were not only problems concerning the hemodialysis apparatus as described above, but also essential problems more important concerning the hemodialysis itself. These are problems of hemodialysis concerning dialysis efficiency such as solute removal, water removal and the like, which are disadvantages unavoidable for the hemodialysis membrane. In conventional hemodialysis, the removal of low-molecular-weight waste products was satisfactory, but as the removal efficiency of medium-molecular-weight was not good, it was provided to use a hollow fiber dialysis membrane with a larger diameter of the hole, to increase the removal efficiency of the medium-molecular-weight solutes. However, by using the dialysis membrane with a large diameter of the hole, the removal of medium-molecular-weight was improved but on the other hand, there were defects that albumin or other protein necessary for a living body were removed together